Reviewed by Darin Adler and Geoff Garen.

        Fix the malloc zone introspection functions so that malloc_zone_statistics does not give
        bogus output in an application that uses JavaScriptCore.

        * kjs/CollectorHeapIntrospector.cpp:
        (KJS::CollectorHeapIntrospector::statistics): Return statistics about memory allocated by the collector.
        * kjs/CollectorHeapIntrospector.h:
        * wtf/FastMalloc.cpp: Zero out the statistics.  FastMalloc doesn't track this information at present.
        Returning zero for all values is preferable to returning bogus data.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@34824 268f45cc-cd09-0410-ab3c-d52691b4dbfc